<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>File Upload</title>
</head>
<body>
<form action="upload" method="post" enctype="application/x-www-form-urlencoded">

    <input type="hidden" value="key123" /><p/>
    <input type="submit" value="Upload">
</form>
</body>
</html>